1. Field of the Invention
The invention relates to bismuth-germanium-oxide materials and somewhat more particularly to such a material with the formula Bi.sub.2 Ge.sub.3 O.sub.9 in crystalline form useful in various devices, such as an x-ray spectrometer crystal or as a photo-acoustic deflector crystal.
2. Prior Art
Russian Journal of Inorganic Chemistry, Vol. 9, No. 2, pages 226-230 (1964) describes the bismuth oxide-germanium-dioxide system and indicates that the phase diagram of Bi.sub.2 O-GeO.sub.2 has stable compounds only for two mixture ratios, namely, at Bi.sub.2 O.sub.3 :GeO.sub.2 ratio of 2:3 and at Bi.sub.2 O.sub.3 :GeO.sub.2 ratio of 7:1.
Journal of Research of the National Bureau of Standards-A. Physics and Chemistry, Vol. 68A, No. 2, pages 197-206 (1964) corrects the Bi.sub.2 O.sub.3 :GeO.sub.2 ratio from 7:1 to 6:1. As to a Bi.sub.2 O.sub.3 :GeO.sub.2 ratio of 1:3, which is relevant to the invention, the prior art established that at such a ratio, only eutectic materials exist. Eutectic materials of this type are inevitably multiphased so that monocrystalline structures from eutectic materials are not possible.